The present disclosure relates to a voltage control circuit that may be applied to a LED device or a power supply.
Generally, in a LED device or a power supply, a detection voltage and a reference voltage are used in order to provide a desired driving voltage.
Although it is desired that such a detection voltage and a reference voltage are not affected by a change in temperature, devices used to detect the detection voltage and devices used to generate the reference voltage have characteristics that vary, depending on a change in temperature.
In order to provide a voltage that is constant regardless of a change in temperature, typical voltage control circuits employ a temperature compensating device such as a thermistor and a semiconductor switch such as a transistor.
By using such typical voltage control circuits, the reference voltage for current feedback may be varied.
In such typical voltage control circuits, however, the threshold voltage of the transistor used as the semiconductor switch may be varied according to a change in temperature and thus the comparison function of the transistor may be deteriorated. Therefore, it is difficult to precisely control the voltage if temperature changes.
Patent Document 1 referenced below relates to a temperature compensation circuit in a modulator, but does not disclose any technical feature to overcome the problem that the voltage control function deteriorates due to temperature characteristics of a transistor.